170 BULLiETIN 15 8, UNITED STATES NATIONAL MUSEUM 



species. Hence it has been deemed advisable to include such genera 

 and species twice in the key, and in several species the two sexes are 

 necessarily separated. The same policy is followed in reference to 

 the families as was adopted for the Calanoida. 



The copepods in this group are very much smaller than the cala- 

 nids, many of them only half a millimeter in total length, or even less. 

 In consequence of this they are exceedingly difficult to dissect, and 

 many authors are satisfied with a superficial examination of the 

 species which they describe. As might be expected, this has resulted 

 in a superabundance of synonyms, the majority of wdiich are specific 

 rather than generic. And in many instances the accurate data are not 

 sufficient to determine the synonymy with any degree of satisfaction. 

 An effort has been made in the key (Appendix B, p. 560) to treat the 

 synonymy conservatively, but it is practically certain that future 

 careful study and the discovery of additional data will change some 

 of the names here adopted. 



Family LONGIPEDIIDAE 



Genus LONGIPEDIA Claus, 1863 



Head fused with first segment, its lateral margins forming broad 

 vertical lamellae inclosing the mouth parts; rostrum large and 

 tongue-shaj)ed. Epimeral plates of second, third, and fourth seg- 

 ments vertical, angularly produced at their posterior corners, and 

 inclosing the bases of the swimming legs. Genital segment with a 

 transverse dorsal median groove, and a sharp spine on each lateral 

 margin just in front of the groove. Anal operculum with a terminal 

 central spine and usually smaller ones on either side. First antennae 

 stout, 5-segmented; exopod of second antennae 6-segmented. First 

 legs smaller than succeeding pairs; second endopods greatly elon- 

 gated; proximal segment of fifth legs with outer fingerlike process 

 and narrow inner expansion, tipped with a single elongate curved 

 seta; distal segment lamellar, with five setae and a terminal spine. 

 One species found here. 



LONGIPEDIA CORONATA Glaus 



Figure 116 



Longipcdia coronata Claus, Die frei lebenden Copepoden, p. Ill, pi. 14, figs". 14— 

 24, 1863.— Saes, Crustacea of Norway, vol. 5, p. 10, pis. 3, 4, 1903. 



Occurrence. — A single female, Penzance Pond, July 9, 1925; two 

 females, shore of Katama Bay, Marthas Vineyard, August 5, 1927. 



Distribution. — Helgoland, Gulf of Naples (Claus) ; Norwegian 

 fiords (Boeck, Sars) ; British seas (T. Scott) ; Suez Canal, Gulf of 

 Manaar (Thompson and Scott) ; North Sea (Timm) ; Scottish coast 



